Older model toilet tanks in homes and apartments can hold up to 12 liters of water and use essentially all of this volume with each flush. With the recognition in recent years that water is a valuable resource and in short supply in many countries, modern toilet tanks have been designed to accomplish toilet bowl evacuation with as little as 3 liters per flush using a half-flush option.
Under the current Australian toilet standards, toilets in the 4.5/3 L class are the lowest volume flush toilets permissible. In overseas markets however, other capacities are commonly available such as 4/2 L dual-flush toilets in Europe and 3/2 L dual-flush toilets in Scandinavia. Such models are unable to be successfully introduced into the Australian market as these classes of toilet are currently ineligible for registration under the current Australian toilet standards (AS 1172.1 and AS 1172.2). Hence, it would be desirable to have a solution which ameliorates this problem by enabling the flush volume to be adjusted to suit Australian and overseas toilet standards.
European Patent No. 2196585 discloses a toilet bowl with flush flow control comprising a toilet bowl, a set of valves and an electric pump. The bowl has an upper rim with an upper valve connected to a first injection duct and a well with a lower valve connected to a second injection duct, whereby water passes through the injection ducts to clean the toilet bowl and well. The set of valves is fed by an electric pump which may or may not be submersed in a flush tank and be controlled by an electronic system.
U.S. Pat. No. 5,216,761 discloses a flush volume control device for flush type toilets equipped with a valve which is opened to allow flush water to flow from the toilet into its bowl and then closed. The flush volume control engages a pivotably mounted, flapper valve bracket as the level of flush water in the toilet tank recedes upon the toilet being flushed and thereafter continues downwardly, displacing the valve to a closed position even though a considerable volume of water may remain in the tank. This provides a reduced volume flush of the toilet bowl. A vertically adjustable float component of the control allows the flush volume to be changed between wide limits at will. This mechanism requires a user to hold the flush lever until the tank is emptied to perform a full flush cycle and can possibly result in using more water if the reduced volume flush was not sufficient in the first instance.
U.S. Pat. No. 5,103,507 discloses a limited flush retrofit control device for toilet tanks suitable for both ball valve tanks and flapper valve tanks. A U-shaped horizontal thrust member with vertical arms attached to each side acts to effect closing of a ball valve or flapper valve. Each vertical arm is fitted with a float, adjusting clips and preferably with weights. The positioning of the clips is adjustable to alter the heights of the float on the vertical arm and determine the flush volume exiting the tank. Again this mechanism requires a user to hold the tank lever arm in the flush position until the tank is emptied to perform a full flush cycle. Furthermore, the device is complicated to adjust the flush volume.
U.S. Pat. No. 8,336,128 discloses a toilet comprising a valve interposed between a pressurized water supply and the toilet bowl for controlling a volume of water flowing from the water supply to the toilet bowl, and a timing mechanism connected to the valve for controlling an amount of time that the valve allows water to flow from the water supply to the toilet bowl. However, this system is complex, expensive to manufacture and difficult to function properly.
Many currently available water efficient toilets, including the inventions which are the subject of the abovementioned patents are comprised of cumbersome parts and/or complicated mechanisms which are costly to install, maintain and replace. Another major disadvantage of the prior inventions is that the selective flushing systems require a user to hold the flush handle or lever in order to empty the water tank and complete the flushing cycle. If the user releases the handle or lever too soon, insufficient water is used to flush the waste and multiple flushes may be required. Such a requirement can result in over flushing or under flushing, which can lead to more water consumption than would otherwise be necessary. Therefore, a need exists for a solution which is easy to use and compact and simple to install, maintain and replace.
The reference to any prior art in this specification is and should not be taken as, an acknowledgment or any form or suggestion that the prior art forms part of the common general knowledge in any country.
In this specification, the terms “comprises”, “comprising” or similar terms are intended to mean a non-exclusive inclusion, such that a water saving toilet system that comprises a list of elements does not include those elements solely, but may well include other elements not listed.